"I always love competing against the world's best. To go against them makes me excited and helps me push myself to go faster, for sure," said Li, who's added an 11th world championships medal to her resume with Sunday's runner-up finish.

As the best female swimmer at the worlds, Ledecky shook hands with Li after the race, gave her a pat on the shoulder during the medal ceremony and acknowledged her Chinese challenger's progress with respect.

"I was a little too focused on the race on one side," said Ledecky, who's racked up 27 world championships medals to tie with her retired countryman Ryan Lochte as the second on the all-time medal list, only behind legend Michael Phelps' whopping total of 33.

"I missed Li on the other side of me, but kudos to her for getting in there. She's been a great competitor all these years. Happy to get the medal. Really fast field. I think the fastest field, first through fourth, we've ever had."

Ledecky was correct about the historic nature of the race.

Entering the evening, McIntosh, Australia's reigning Olympic champion Ariarne Titmus and Ledecky were the only women to ever break 3:59, but the results from Li and fourth-placed Aussie Lani Pallister have moved them to fourth and fifth, respectively, in the rankings of fastest 400m free performances in history.

From her sensational international debut in 2017, to reaching the all-time top-5 this year, Li's navigated through anything but still waters, having to battle hard against injuries, conditioning issues and a slump in results during a tough three-year struggle since the end of 2018.